The purpose of this thread is to document my listening room, equipment, and the listening room's audio performance. It is not intended for feedback, although if you have any questions, I will be happy to answer them.

The purpose of this post is to show the interaction of multiple subs in the listening environment, and how careful placement and tuning can result in a significant improvement in bass response. The subs used in this analysis are four Hsu Research ULS-15 sealed subs. The subs are placed in the listening room as per the diagram in the first post in this thread. The two front subs are at the 1/4 and 3/4 spots along the front wall, and the two rear subs are collocated at approximately the center of the back wall. The two front subs are equidistant from the MLP, and are connected to the sub1 input on a MultEQ XT32 AVR with Sub EQ HT. The two rear subs are also approximately equidistant from the MLP, on the Sub2 input on the AVR. The two front subs are gain-matched to each other, and the two rear subs are gain-matched to each other. However, the level of the rear subs is 5dB lower than the two front subs, because they are significantly closer to the MLP.

The measurement of the subs independent of each other, and as front and rear pairs, reveals that the in-room response (without room correction) is not very smooth.

Individual subs:

Sub Pairs:

However, when all fours subs are driven at the same time, we start to see advantages in the summed response:

And Audyssey room correction puts the final smoothing on the response:

And finally, combined response including center channel:

This analysis clearly shows the benefits of multiple subs in the listening environment.

To add some historical perspective, here is what the bass response looked like in October 2011, when I had only two subs, and no bass treatments in the listening room.

Just curious, why do you have the L/R at +/- 45 degrees? That's pretty wide (usually 30 is plenty). Considering you also have wide speakers (at +/- 65) it does not seem you'd be lacking for width cues.

Just curious, why do you have the L/R at +/- 45 degrees? That's pretty wide (usually 30 is plenty). Considering you also have wide speakers (at +/- 65) it does not seem you'd be lacking for width cues.

Roger,

Perhaps you are miss-interpreting my drawing.

The front speakers are at an angle of 27.3 degrees, and the Wides are at an angle of 51.2 degrees, which is actually a narrower angle than the recommendation.

No harm done. It is just a PowerPoint drawing, so no way to draw it to scale. I used to use AutoCAD when I was working, but don't want to spend the money for a personal license. If you know of a good consumer-class (read: inexpensive or free) CAD program, I would welcome the recommendation. In the meantime, I determine angles by using a spreadsheet that calculates the angles from the distances of the legs of the triangle.

No harm done. It is just a PowerPoint drawing, so no way to draw it to scale. I used to use AutoCAD when I was working, but don't want to spend the money for a personal license. If you know of a good consumer-class (read: inexpensive or free) CAD program, I would welcome the recommendation. In the meantime, I determine angles by using a spreadsheet that calculates the angles from the distances of the legs of the triangle.

If you like to have the option for 3D rendering, try SweetHome3D. I found it much easier than Sketchup.

Great Looking (& sounding ) room, came here from the link in your sig & your suggestion in the REW thread about a month ago - trying to get caught up as we speak so I may join the discussion.. just started measuring a few weeks ago after a lot of lurking & learning..

Damn AustinJerry that is one beautiful setup you have. I would have bought the X900A myself but went with its 55inch sibling the 55W900A which like the X900A is a beautiful tv. IMHO the 2 best tv's made by Sony. Again though very nice setup.

I was wondering if you might be able to share your process in choosing acoustic treatments. I am in the early stages of planning acoustic treatments, and am trying to figure out what I need.

Did you try to place as many bass traps as you could, given that you have 4 potent subs, or did you follow the REW measurements, or something else?

Treatments accomplish two things--they reduce bass resonance, and they tame reflections in the spectral region. The guidelines for treatments to control bass resonance are to 1) choose treatments designed specifically for the longer hass frequencies (which are generally thicker), and 2) to place the treatments in the most effective locations, at the intersection of multiple surfaces, e,g. room corners, wall to ceiling, etc. Also, the more traps, the more effective the resonance control.

Treatments for spectral reflections are different. The treatments themselves must be full-spectrum treatments, and they are placed at spots specifically associated with reflections. You can analyze room reflections using the REW ETC measurement.

There are threads here on AVS that provide more specific guidance on effective room treatment.

Treatments for spectral reflections are different. The treatments themselves must be full-spectrum treatments, and they are placed at spots specifically associated with reflections. You can analyze room reflections using the REW ETC measurement.

There are threads here on AVS that provide more specific guidance on effective room treatment.

Thanks. The trouble with many of the posts on here is that often the advice is specific for a that applicaiton, rather than unifying ideas. Although I have been reading up on hometheatershack, the guide that you have in your sig ( Getting Started with REW: A Step-by-Step Guide ) has been the most helpful and concise guide for using and understanding the REW I could find. Thank you very much for putting it together.